____ and he?

Just now someone asked me if it was proper, in her essay about Prospero, to say that “He and Ariel . . .”
Her question was about whether to use ‘he’ or ‘him’, but it made me wonder. In formal writing I might intuitively switch the order to “Ariel and he . . .” to parallel “___ and I”, but is it actually any more formal?

In less formal writing, I prefer to ignore the I rule altogether and list whoever comes to mind first or is most important. It’s a silly rule anyway. ^_^

I don't know if this is a rule or not, but if it were the subject of the sentence, I would use "he and Ariel...", not "Ariel and he...", that is, I would not try to parallel the "I comes last" rule. The reason I would do it this way, is "he" is singular and "he and Ariel" is now plural. If "he" comes after "Ariel" then you would have the singular "he" followed by the plural form of the verb. Now, this would not be incorrect gramar, but it might be awkward to say: Ariel and he have funny names. The "... he have..." might sound strange even if correct.

*Is* it just a courtesy? "That idiot and I are going to come to blows" sounds more natural to me than "I and that idiot are going to come to blows," and there's certainly nothing Miss Manners-approved about either version.